Because time for sleep in our life usually consumes about one third of our entire lifetime, proper rest is necessary. Proper rest is important, for example, when travelling long distances through different time zones. Only sufficient sleep can restore our mental and physical fatigues so as to efficiently carry out one's daily tasks.
It is a universal paradigm that parents of this world love and take care of their children. However, one of the most common headaches or problems in taking care of children is to properly cover them with a blanket or the like so that a sleeping child is adequately covered; and to prevent that the blanket is improperly removed, either in winter or summer time. When a sleeping child kicks off the blanket, the child is liable to catch cold, or is otherwise discomfortably affected. In order to prevent the children from being so affected, the parents can not help but get up periodically during the night and repeatedly check if the children's blanket have been kicked off or not. As a result, the parents are seldom allowed, during the growing period of their children, to have a full and relaxed sleep. This problem not only causes the parents considerable mental stress, but may also adversely affect their full work efficiency.
For adults catching cold as a result of kicking off the blanket during sleeping is also a common problem. In the final analysis, catching cold as a result of kicking off the blanket during sleeping is a general problem, and there has remained a need for determining if a blanket or the like has been kicked off by a baby, or a sleeping person.